不同施氮量条件下烤烟叶面积系数与冠层光谱参数的相关性

Correlation of Leaf Area Index with Canopy Reflectance Spectrum of Flue-cured Tobacco Under Different Nitrogen Application Rate

为明确氮肥施用量对烤烟叶面积系数(LAI)和冠层光谱参数的影响,测定了不同氮肥施用量条件下烤烟不同生育期的冠层光谱特征和LAI,对二者随施氮量的变化进行了分析,并利用相关分析和回归分析确定了二者的相关性。结果表明:在一定的施氮量范围内,施氮量增加对烤烟LAI有明显的促进效应,但在打顶期的效应不及团棵期和旺长期明显;一定范围内随施氮量增加,烤烟冠层光谱中可见光波段的反射率降低,而近红外波段的反射率提高;可见光范围内500,550,600,650和670 nm处反射率与LAI呈极显著负相关,近红外区域内780和800 nm处反射率与LAI呈显著正相关1,050和1100 nm处反射率与LAI呈极显著正相关,与LAI相关性最强的植被指数为NDVI(10505,50),用其构建的回归模型预测效果较好。

To confirm the effects of different nitrogen application rate on leaf area index（LAI） and canopy reflectance spectrum of flue-cured tobacco,the canopy reflectance spectrum and LAI in spherical plant stage,fast growing stage and topping stage were determined,and the correlation between them was analyzed.The results showed that： within a certain range of nitrogen application rates,LAI was promoted obviously with the increase of nitrogen fertilizer application rate during the three growing stages,while the promotion effect in topping stage was not as obvious as in the other two stages;the reflection in visible band decreased and the reflection in near infrared band increased with the increase of nitrogen application rate within a certain range;in visible light band,LAI extremely significantly negatively correlated with the reflectivity at 500,550,600,650 and 670nm;in near-infrared band,LAI significantly positively correlated with the reflectivity at 780 and 800nm,extremely significantly positively correlated with the reflectivity at 1050 and 1100nm;the vegetation index,which strongly correlated with LAI,was NDVI（1050,550）.The regression model established based on that showed better prediction effect.